Such a seat comprises, if it is a chair, a seat element, a backrest and four legs with, in addition, if it is an armchair, two armrests.
In order to strengthen the chair, the seat element presents a generally double band of subjacent ribs integral with the legs.
Such chairs are stackable for transport thereof in the form of a bound-up pile and for storage thereof. To that end, the legs are slightly inclined with respect to the vertical and the projection of the ribs is limited to the stacking pitch.
Injection of the chair is advantageously effected by means of a hot transfer nozzle retractably traversing the fixed part of the mould, which fixed part defines, particularly in the vicinity of said nozzle, conduits connected to a cooling circuit.
A first moulding technique consists in injecting the matter behind the rounded part where the seat element joins the backrest. The drawback of this is that defects in appearance are apparent at that spot on the finished chair.
In order to overcome this drawback, a second moulding technique consists in injecting the matter at the bottom of the rear rib. In that case, there is a major difficulty in housing in the fixed part of the mould beneath the impression defining the rounded joining part, the passage of the hot nozzle and the cooling conduits. In order satisfactorily to overcome this difficulty, the height of the ribs must exceed a certain limiting value. In that case, defects in appearance may be apparent, but this is not detrimental since they are, in principle, located at a spot hidden from view.
In any case, the lack of space is obvious when, for various reasons and in particular in order to increase the stacking capacity, the height of the ribs is reduced in correspondence with the stacking pitch.
It is an object of the present invention to overcome this drawback by increasing the distance from the point of injection to the rounded part joining the seat element to the backrest, whilst limiting the height of the ribs and even reducing it. Concomitantly, it envisages improving the quality of the product injected and its appearance, promoting the flow of the rainwater so that it does not stagnate on the seat element, rendering it easy to carry a chair, and even several stacked chairs, with one
structure despite the reduction of its thickness.